NEW YORK, March 12 (Reuters) - The S&P 500 and the Dow Jones Industrial Average slumped on Monday as the U.S. tariffs signed into law last week by President Donald Trump weighed on industrials, though gains in tech stocks boosted the Nasdaq.

Shares of companies such as Boeing Co, down 2.9 percent, and Caterpillar Inc, down 2.4 percent, have been under pressure as Trump's protectionist stance on steel and aluminum imports could increase costs and hamper sales abroad. Boeing and Caterpillar were the biggest decliners on the Dow.

Trump last week softened his stance on tariffs by exempting Canada and Mexico, and negotiations were ongoing as the European Union and Japan also seek exemptions.

"The big multinational, industrial companies of the world are all taking a hit on the concern that they will be the targets of reprisal sanctions," said Robert Phipps, a director at Per Stirling Capital Management in Austin.

Concerns about possible fallout from the tariffs largely supplanted optimism, based upon the modest wage growth numbers from Friday's employment report, that the Federal Reserve would stick to its projected three interest-rate increases in 2018.

"We've seen stable, modest wage growth, nothing that should be considered harmful for equity markets," she said.

"Growth stocks are doing well. It's pretty much a continuation of last year's rally, whereas the Dow has all sorts of other companies that may not be growth-oriented."

The Dow Jones Industrial Average fell 157.13 points, or 0.62 percent, to 25,178.61, the S&P 500 lost 3.55 points, or 0.13 percent, to 2,783.02 and the Nasdaq Composite added 27.52 points, or 0.36 percent, to 7,588.33.

Even with the session's losses, the S&P 500 is just 3.1 percent below record highs hit on Jan. 26, while the Nasdaq has recovered its losses from last month's sell-off.

The tech-heavy Nasdaq was lifted in part by further signs of official disapproval of Broadcom Ltd's $117 billion bid for U.S. graphics chipmaker Qualcomm Inc.

The U.S. Treasury said in a letter to Singapore-based Broadcom that it had confirmed national security concerns about the bid and that the company had not given sufficient notice of its plans to redomicile in the United States.

Broadcom gained 3.6 percent while shares in Qualcomm were flat.

Shares of Micron Technology rose 8.8 percent to $59.37 after analysts at Nomura raised their target for the stock to $100.

Advancing issues outnumbered declining ones on the NYSE by a 1.22-to-1 ratio; on Nasdaq, a 1.45-to-1 ratio favored advancers.

The S&P 500 posted 61 new 52-week highs and no new lows; the Nasdaq Composite recorded 211 new highs and 24 new lows.

Volume on U.S. exchanges was 6.52 billion shares, compared to the 7.2 billion average for the full session over the last 20 trading days. (Additional reporting by Sruthi Shankar in Bengaluru; Editing by Nick Zieminski and Cynthia Osterman)